Cerebral and systemic hemodynamic changes during cognitive and motor activation paradigms

Area of Science:

• Neuroscience
• Physiology
• Cerebrovascular Research

Background:

• Brain activation typically increases cerebral blood flow (CBF) due to metabolic demand.
• Existing models often overlook concurrent changes in arterial blood pressure (ABP) and arterial PCO2 during brain stimulation protocols.

Purpose of the Study:

• To investigate if changes in arterial blood pressure (ABP) and arterial PCO2 occur during brain activation.
• To determine if these physiological changes contribute to cerebral blood flow velocity (CBFV) alterations.
• To test if a pressure-autoregulatory response accompanies metabolic-driven changes in CBFV.

Main Methods:

• Continuous recordings of CBFV in middle cerebral arteries (MCA), ABP, ECG, and end-tidal PCO2 (Pet(CO2)) in 15 healthy subjects.
• Subjects underwent word generation and constructional puzzle tasks known to induce lateralized cortical activation.
• Analysis included derived cerebrovascular resistance and hemispheric CBFV differences (CBFV(R-L)).

Main Results:

• Both word generation and puzzle tasks induced significant increases in CBFV, ABP, and heart rate, alongside decreases in Pet(CO2).
• The word generation task showed greater left hemispheric dominance in CBFV changes compared to the puzzle task's right hemispheric dominance.
• No adaptation of the CBFV(R-L) difference was observed with repeated task presentations.

Conclusions:

• Significant changes in ABP and Pet(CO2) occur during brain activation, contributing to CBFV changes.
• A pressure-autoregulatory response is evident alongside metabolic-driven hemodynamic changes.
• The interplay of PCO2 and heart rate variations necessitates refined models for understanding brain activation responses.